How is it that finish carpenters do trim jobs daily without suffering angle-induced embolisms? Easy—because they rely on miter guides, not their eyeballs, to tell them where to cut. Likewise, framing carpenters use squares to determine the angles for rafters, rakes, and stair stringers; and furniture makers consult their protractors before laying out dovetails.

What Tool Do You Use to Find Angles?

The right angle-finding tool is your protection against loose joinery and expletive-filled outbursts, whether you’re doing something big like building a garden shed, or simply tackling around-the-house maintenance tasks like measuring for a storm window.

So before you make another unsightly cutting mistake, put down that caulk tube and pick up one of the measuring tools. The old adage—”Measure twice”—still applies. But you also need to know the angles.

10 Angle Measuring Tools

1. Pivot Square

The aluminum Pivot Square has a locking, adjustable leg that firmly holds any angle from 0 to 90 degrees, so you can make repeated, consistent mark or guide your circular saw through marks or guide your circular saw through angled crosscuts. Spirit vials help you check for level, as when establishing the angle to cut siding where it meets a roofline. About $84, C.H. Hanson

2. Three-Sided Squares

Photo by Mark Weiss

Simple, durable, and full of roof-layout info, the Speed square is a carpenter’s classic. Use it to find angles, mark cutlines, and as a crosscut guide to keep your saw straight. Stick with the aluminum alloy version, not plastic: It’s more rugged, and the stamped numbers are easier to read. About $10, Swanson Tool Co.

3. Square Shooter

Photo by Mark Weiss

This layout weapon for wide pieces of lumber has a sliding knob along its semicircular arc. Lock the triangle at the desired degree, then press it and a fixed knob on the handle against the edge of the work. The 12-inch blade can’t wobble or pivot as it guides your pencil or your saw.

About $12, Empire Level

4. T-Bevel

Photo by Mark Weiss

Lock the T-bevel’s sliding blade against any angle, then use the tool to copy that angle onto your work or to set the angle of a saw blade. This T-bevel’s blade locks in place with a recessed bronze latch (as opposed

to the usual wing nut) so either side can lie flush as you’re marking your layout.

About $45, Lee Valley

5. T-Bevel Setter

Photo by Mark Weiss

T-bevels, which have no markings, are great for matching and transferring angles but can’t tell you exactly what those angles are. To find out, align the bar on this guide with the T-bevel’s blade and read the angle to half a degree. Or set a desired angle and align the bevel’s blade with it.

About $32, Lee Valley

6. Bevel Protractor

Photo by Mark Weiss

Starrett’s cast-iron protractor head with chromed-steel rule, on the market since 1908, is a classic machinist’s tool for anyone who values precise layout marks. The rotating 180-degree head locks the rule at a desired angle or tells you the exact angle of an existing bevel.

About $113, Starett

7. Digital Protractor

Photo by Mark Weiss

Bosch’s digital angle finder is arguably the most accurate tool we tested, and certainly the most idiot proof. Press each of its legs into a corner and get a digital readout to a tenth of a degree. The tool comes with two vials so you can be sure it’s level on both sides of the corner as you take a reading.

About $130, Bosch

8. Protractor Plus

Photo by Mark Weiss

Starrett’s updated combination protractor takes the guesswork out of cutting crown molding. Place each leg on an adjacent wall, and arrows at the pivot show the degree setting you need to make a butt joint, or the angle to miter each piece. Comes with a table of compound miter angles.

About $90, Starrett

9. Miter Guide

Photo by Mark Weiss

Press this simple tool’s legs flush against any inside or outside corner. Internal gears position a protruding metal tab to bisect the angle. Now take the guide to your miter saw, brace one leg against the fence, then line up the saw blade against the tab. You’ve just set the exact miter angle.

About $15, Rockler

10. Adjustable T-Square

Photo by Mark Weiss

Improving on the old 4-foot squares that could only mark 90-degree cuts in drywall, OSB, plywood, and other sheet goods, this adjustable square has markings for 30, 45, and 90 degrees. Or you can set it to any angle between 0 and 180 degrees. Folds for easy transport.

About $40, Johnson Level